Linux drivers development
From ArmadeusWiki
This page summarizes all you need to know before starting to develop Linux drivers for your Armadeus board
Contents
[hide]Recommended reading before starting
We advise you to read (not necessarly understand ;-) ):
- Linux Device Drivers (3rd edition) book: http://lwn.net/Kernel/LDD3/
Adding your own drivers
Our custom drivers build is integrated to the Linux build system (kbuild). You can select, in the linux "menuconfig"/"xconfig" tool, which Armadeus drivers you want to add on your target. (only gpio, ppdev & ps2keyboard are integrated yet).
Here is the way to add custom drivers:
- in armadeus/target/linux/modules/, add a directory for you driver (ex toto/)
- put reference to this directory in the armadeus/target/linux/modules/Makefile and armadeus/target/linux/modules/Kconfig files
- in toto/ put your driver source code and create 2 files, Kconfig and Makefile. (Use armadeus/target/linux/modules/gpio/Makefile & Kconfig as examples.)
To compile the modules, either launch:
- "make" in armadeus/target/linux/modules/ directory
or
- "make linux" in armadeus/
only "make linux" will install the modules in target rootfs image
i.MX register access from driver
To access i.MX registers from your driver, please use the macros defined in:
#include <arch/arm/imx-regs.h>
For example (access to PWM control register):
//enable the PWM PWMC |= PWMC_EN;
Debug
Activate debug messages (from pr_debug() function) on console:
# echo 8 > /proc/sys/kernel/printk
